This invention relates to an improvement in a printing machine, (e.g. an electrostatic reproduction machine) but more particularly, to a printing machine having an improved flexible counter control system.
In the practice of xerography as described in U.S. Pat. No. 2,297,691 to Chester F. Carlson, a xerographic surface comprising a layer of photoconductive insulating material affixed to a conductive backing is used to support electrostatic images. In the usual method of carrying out the process, the xerographic plate is electrostatically charged uniformly over its surface and then exposed to a light pattern of the image being reproduced to thereby discharge the charge in the areas where light strikes the layer. The undischarged areas of the layer thus form as electrostatic charge pattern or latent image in conformity with the configuration of the original pattern.
The latent electrostatic image may then be developed by contacting it with a finely divided electrostatically attractable material, such as a resinous powder. The powder is held in the image areas by the electrostatic fields on the layer. Where the field is greatest, the greatest amount of material is deposited; and where the field is least, little or no material is deposited. Thus, a powder image is produced in conformity with the image of the original being reproduced. The powder is subsequently transferred to a sheet of paper or other transfer member and suitably affixed to thereby form a permanent copy.
The latest concept for electrostatic reproduction machines utilizes high speed flash exposure of a document, and a moving photoconductive material in the form of an endless belt which is continuously charged. Additionally, such reproduction machines are provided with a developing system which supplies toner particles in relatively large quantities for solid area coverage, such as a magnetic brush developing apparatus. Thus, after the belt passes the magnetic brush assembly for example, a xerographic powder image is formed on the belt which corresponds to the electrostatic latent image. This powder image is then transferred to a support surface (e.g. a sheet of paper) to which it is fused by a fusing assembly whereby the powder image is caused to adhere to the support surface permanently.
The latest reproduction machines are high speed machines which print copies at a rate substantially in excess of any previous machines. Because of this capability, and because the customer is sometimes charged on the basis of the copies made, it is highly desirable that such machines be flexible enough so that any one of various billing schemes can be used to assure that the customer can take advantage of the economies which are possible with such high speed machines. Thus, a counter control system is needed which can be easily programmed to operate so as to record whatever information is needed for the billing scheme selected. Such a control system also has the advantage of allowing the user of a machine to determine if the latter is being efficiently utilized. For example, the user can determine the ratio of running time to standby time, or what type of runs are being made on the machine, either of which affects machine wear.